1. Field of the Invention
This invention relates to an effect imparting device, and an electronic musical instrument incorporating the same, and more particularly to an effect imparting device for imparting effects to signals transmitted via a plurality of channels, and an electronic musical instrument incorporating the same.
2. Prior Art
Conventionally, electronic musical instruments can impart effects, such as tremolo and vibrato, to musical tones when they are generated. However, these conventional effects cannot produce sufficient variation to musical tones, and therefore, a novel effect imparting circuit (effecter) has been demanded. Recently, to meet such a demand, an effecter utilizing a DSP (Digital Signal Processor) has been developed, which is capable of imparting a variety of effects, such as chorus, flanger, distortion, and reverberation, to musical tones, each of which effects requires complicated arithmetic operations.
Now, description of a conventional electronic musical instrument will be made with reference to FIG. 2 schematically showing the arrangement of the convential electronic musical instrument. FIG. 2 includes a novel feature of the electronic musical instrument according to the invention, which will be described in detail hereinafter.
In the figure, a CPU (Central Processing Unit) 1 sequentially reads out and executes programs stored in a ROM (Read Only Memory) 9 to thereby control the operation of the electronic musical instrument. The ROM 9 stores tone color parameters, effect parameters, etc. in addition to the programs. The instrument also includes a RAM (Random Access Memory) 8 for temporarily storing variables and other data required by the CPU 1 in executing the programs.
A panel 3 is comprised of a switch group 3a formed of a plurality of switches, and an operating element group 3d formed of a plurality of operating elements. The switch group 3a includes two switches, labelled BP1 and BP2, 3c and 3b which have not been conventionally used but are provided according to an embodiment of the invention, described in detail hereinafter.
A keyboard 7 is comprised of a plurality of keys and a large number of switching circuits periodically scanned for various kinds of information concerning key-depressing and key-releasing operations performed by a player. When the player depresses a key or releases the same, signals indicative of information of a key code, a velocity, and an after touch on the key depressed or released are immediately generated and sent via an address/data bus 2 to the CPU 1.
The CPU 1 performs data processing according to a program, based on the signals received from the keyboard 7 to thereby determine parameters for control of a TG (Tone Generator) 4 and sends the same via the address/data bus 2 to the TG 4. The TG 4 generates a musical tone signal according to the parameters supplied by the CPU 1 and sends the same to an effecter 5. The effecter 5 imparts various kinds of effects to the musical tone signal and delivers the resulting signal to a SS (Sound System) 6. Details of the effecter 5 will be described hereinbelow. The SS 6 converts the signal, which is digital, received from the effecter 5, into an analog signal, which is then amplified by a power amplifier thereof, not shown, to a predetermined level, and finally converted into an acoustic signal, whereby a musical sound is generated.
Details of the effecter 5 will be described with reference to FIG. 1 in which blocks designated by the same reference numerals as in FIG. 2 represent means having the same functions as corresponding ones in FIG. 2. The effecter 5, which is implemented by a DSP, is divided according to functions into an assigner 12, tone color effect-imparting blocks 13, 14, sound field effect-imparting blocks 15, 16, multipliers 17 to 20, an adder 21, and an effect control block 11. The effect control block 11 controls operations of the other blocks of the effecter 5, by the use of parameters which are set or changed according to directions supplied via the address data bus 2 from the CPU 1.
The TG 4 delivers musical tone signals, more specifically, digital musical tone signals representative of musical tones having N kinds of respective tone colors different from each other, to the assigner 12, independently of, or separately from each other. The assigner 12 assigns each of the musical tone signals to either of two outputs thereof to thereby deliver two output signals therefrom. The two output signals from the assigner 12 are each divided into two branch signals whereby the branch signals are supplied to the multiplier 17, the tone color effect-imparting block 13, the multiplier 19, and the tone color effect-imparting block 14.
The tone color effect-imparting blocks 13, 14 impart effects for modifying tone colors, such as distortion, chorus, and flanger, to corresponding branch signals from the assigner 12. Selection from these effects and determination of characteristics of selected effects are performed by parameter values delivered from the effect control block 11 responsive to directions supplied via the address/data bus 2 from the CPU 1. Output signals from the tone color effect-imparting blocks 13, 14 are delivered to the sound field effect-imparting blocks 15, 16, respectively. The sound field effect-imparting blocks 15, 16 impart sound field effects, such as reverberation, in most cases, to the output signals from the preceding blocks. Modifications of reverberation characteristics are performed by changing parameter values supplied from the effect control block 11 directed via the address/data bus 2 by the CPU 1.
The output signal from the sound field effect-imparting block 15 is input to the multiplier 18. For the purpose of volume balance adjustment, the multipliers 17 and 18 multiply one of the branch signals from the assigner 12 and the output signal from the sound field effect-imparting block 15 by respective coefficients (parameter values) delivered from the effect control block 11. The resulting signals are both delivered to the adder 21. Similarly, the output signal from the sound field effect-imparting block 16 is input to the multiplier 20. For the purpose of volume balance adjustment, the multipliers 19 and 20 multiply the other of the branch signals from the assigner 12 and the output signal from the sound field effect-imparting block 16 by respective coefficients (parameter values) delivered from the effect control block 11. The resulting signals are both delivered to he adder 21.
The adder 12 adds up the four signals delivered from the multipliers 17 to 20, and delivers the resulting signal to the SS (sound system) 6, where it is converted into an analog signal, amplified to a predetermined level, and finally converted into an acoustic signal, whereby a musical sound is generated.
The effect control block 11 receives signals indicative of various kinds of control information (directions) via the address/data bus 2 from the CPU 1, and delivers control signals (parameter values) to the assigner 12, the tone color effect-imparting blocks 13, 14, the sound field effect-imparting blocks 15, 16, and the multipliers 17 to 20, according to the kinds of control information.
Now, let it be assumed as a typical example that the tone color effect-imparting block 13 and the sound field effect-imparting block 15 of the effecter 5 shown in FIG. 1 are set to impart distortion and room reverberation, respectively, and the tone color effect-imparting block 14 and the sound field effect-imparting block 16 of the same to impart chorus and room reverberation, respectively. If a signal representative of a musical tone having a tone color of guitar is delivered from a channel ch1 of the TG 4, the assigner assigns this signal, for example, to the tone color effect-imparting block 13, and another signal representative of a musical tone having a tone color of strings to the sound effect-imparting block 15.
According to these settings, the tone color effect-imparting block 13 modifies the tone color of guitar into a distortion guitar tone, while the tone color effect-imparting block 14 modifies the tone color of strings into a multichannel ensemble strings tone. Further, the sound field effect-imparting blocks 15, 16 properly impart reverberation to the resulting signals, thereby causing a desired musical tone to be generated. A degree of reverberation imparted by the sound field effect-imparting block 16 is often set to a larger value than a degree of reverberation imparted by the sound field effect-imparting block 15 (i.e. the coefficient used in the multiplier 20 is made larger than that used in the multiplier 18), thereby making the feeling of ensemble conspicuous.
In the above example, distortion and chorus are examples of tone color effects to be imparted to a musical tone to be generated. However, there are cases in which other tone color effects, such as flanger and phaser, are desired, depending on the tone colors of musical tones represented by musical tone signals delivered from the TG 4. Recently, some electronic musical instruments have tone generators each adapted to generate e.g. as many as 16 kinds of musical instrument tones and deliver them via 16 channels at the same time. Ideally, 16 different tone color effect-imparting blocks are required for respective 16 channels from the tone generator. Further, to achieve settings for imparting suitable degrees of reverberation to the respective tones, it is necessary to provide 16 sets each comprised of a tone color effect-imparting block and a sound field effect-imparting block connected in series as shown in FIG. 1, which leads to a much increased size of an electronic musical instrument.
Further, some conventional effecters and electronic musical instruments are each equipped with a bypass switch for bypassing means for imparting effects to musical tone signals. However, this bypass switch causes musical tone signals to bypass both a tone color effect-imparting block for imparting a tone color effect to modify a tone color and a sound field effect-imparting block for imparting a sound field effect to create a particular sound field. Consequently, even if only a sound field effect for generating a sound field is desired to be imparted to the musical tone signal by an external effecter, the tone color effect as well ceases to be imparted to the musical tone signal, causing musical tones to be delivered in their incomplete state.
The bypass switch is advantageous in that musical tones to which are imparted various kinds of effects can be compared by listening with a musical tone having no effects, by operating the bypass switch in a one-step manner. More specifically, this function is realized by setting the coefficients to be supplied to the multipliers 17, 19 in FIG. 1 to "1" and the coefficients to be supplied to the multipliers 18, 20 in the same to "0", in response to pushing of the bypass switch. To effect a fine adjustment of the tone color effect-imparting block, it is desirable to cause the musical tone signal to bypass the sound field effect-imparting block alone, which, however, cannot be effected by the conventional effecter, so that the fine adjustment requires laborious works, e.g. of adjusting the tone color effect-imparting block after setting the degree of reverberation to be effected by the sound field effect-imparting block to zero, and then adjusting again the reverberation to a proper degree. Further, if it is desired to impart the sound field effect alone to the musical tone, while bypassing the tone color effect-imparting block, for the purpose of adjustment of tone quality thereof before it is input to the effecter, much labor is required in adjusting operations, as well.
Furthermore, although some conventional electronic musical instruments are adapted to change effects to be imparted to a musical tone simultaneously with a change of the tone color of the musical tone to be generated, they change the whole effect-imparting program, which prevents them from individually changing tone-color modifying effects in a manner corresponding to a change in the tone color, especially in performing an automatic performance using many tone colors.
Some conventional electronic musical instruments have output terminals provided for respective signals representative of tone colors, which permits the instruments to be connected to an external effecter. However, they are not adapted to utilize effecters incorporated therein for modification of the tone color.